1. Field of the Invention
This invention relates to a vibrator controlling circuit which is used in a portable telephone to notify a user of an incoming call.
2. Description of the Related Art
In portable telephones, notice of an incoming call has been widely carried out by sounding a ringing tone. However, since this causes other people annoyance in a meeting or on a train, notice of an incoming call has also been widely carried out by vibration of a spring vibrator recently.
FIG. 4 shows a conventional vibrator controlling circuit for vibrating a spring vibrator. When a calling signal is received by an antenna 1, a calling signal detection circuit 2 detects this calling signal and a power-supply voltage VDD is applied to a spring vibration control integrated circuit 3.
Waveform (A) in FIG. 3 shows a square-wave signal used in the conventional vibrator controlling circuit of FIG. 4. When a power-supply voltage VDD is applied to the spring vibration control integrated circuit 3, a square-wave signal as shown in (A) is generated from the spring vibration control integrated circuit 3. This square-wave signal is applied to a gate electrode of an N-channel MOSFET 4. Thereupon, the N-channel MOSFET 4 repeats an ON/OFF operation in that the same is turned on every time a square-wave signal is applied and is turned off when it disappears, and an intermittent power-source voltage VDD is applied from a power source to a spring vibrator 5.
FIG. 2 shows a spring vibrator 5 used in the conventional vibrator controlling circuit of FIG. 4. When an electric current flows through a coil 6 of the spring vibrator 5, this coil 6 is magnetized due to electromagnetic induction. When the coil 6 is magnetized, a magnet 9 in a leaf spring 8 provided on a substrate 7 is attracted. When the square-wave signal applied to the gate electrode of the N-channel MOSFET 4 becomes low level, the N-channel MOSFET 4 is turned off, and the electric current to the coil 6 is intercepted. When the electric current to the coil 6 is intercepted, the spring vibrator 5 is restored by resilience of the leaf spring 8. By repeating such an operation, the spring vibrator 5 vibrates and gives notice of an incoming call.
As mentioned above, when a calling signal is detected by the calling signal detection circuit 2, a power-source voltage VDD is applied to the spring vibration control integrated circuit 3, the N-channel MOSFET 4 is turned on/off, and an intermittent electric current is supplied to the spring vibrator 5, whereby the spring vibrator 5 is vibrated to give notice of an incoming call.
When the vibration of the vibrator 5 is switched off, a mere stop of the electric current to the spring vibrator 5 still allows the vibration of the leaf spring 8 to last for some time due to inertia of the structure, especially a weight 10 for a proper vibration of the leaf spring 8. This uncontrolled continued vibration is not desirable.
The invention provides a vibrator controlling circuit including a spring vibration control integrated circuit generating a first intermittent signal, a switching element performing an on and off operation based on the first intermittent signal applied by the spring vibration control integrated circuit, a spring vibrator vibrating based on the on and off operation of the switching element, and a cycle delaying signal generating circuit applying a delay signal to the spring vibration control integrated circuit when the vibration of the spring vibrator is forced to stop. The spring vibration control integrated circuit applies to the switching element in response to the delay signal a second intermittent signal which is a reversal of the first intermittent signal.
The invention also provides a vibrator controlling circuit including a spring vibration control integrated circuit generating a first square-wave signal when a calling signal is detected, a metal oxide semiconductor filed effect transistor performing an on and off operation based on the first square-wave signal applied by the spring vibration control integrated circuit, a spring vibrator vibrating based on the on and off operation of the transistor, and a cycle delaying signal generating circuit applying a delay signal to the spring vibration control integrated circuit when the calling signal is not detected, the spring vibration control integrated circuit applies to the switching element in response to the delay signal a second square-wave signal which has a phase shifted from a phase of the first square-wave signal.